The present invention relates to a printer and, more particularly, to a printer which makes it possible to effect a multi-item validation printing.
Furthermore, the present invention relates to an electromagnetic plunger-type printing device for effecting printing by hammering in the printer.
And the present invention relates to a cutter device for a receipt paper in the printer.
Still furthermore, the present invention relates to a mounting arrangement of an optical detector having luminous and light receiving elements effective to the control of the operation of the printer.
A variety of printers of the type in which a receipt paper and a journal paper are arranged in parallel to each other have been proposed, but any one of the prior art printers of the above type is so designed that the receipt paper is printed by a receipt paper printing drum, then fed upwardly and lastly cut by a moving cutter transversely. In the prior art printer of the design, the printed receipt paper is fed upwardly along the associated printing drum and cut in the fed position, and accordingly, scraps generated in the receipt paper cutting drop and tend to adhere to the printing drum resulting in improper printing. And since the receipt paper is cut transversely in the upwardly fed position, receipt paper sections cut off the rest of the receipt paper leap and accordingly, it is necessary to manually take these cut receipt paper sections out of the printer and such manual operation is inconvenient.
Printers combined with both receipt paper and journal paper printing drums or either one of the printing drums so as to effect validation printing have been also proposed, but the printer of this type is also basically the above-mentioned printer having a validation printing mechanism added thereto and has the same disadvantages as those inherent in the above-mentioned printer and is capable of effecting only the last validation item, for example, of a multi-item validation printing because the printer is designed to feed the receipt paper upwardly which is unsatisfactory from the viewpoint of practical use.
Furthermore, it has been also known of the printing device of a printer of the type in which a receipt paper and a journal paper are transferred along their respectively associated printing drums and a selected hammer of the printing device disposed on the side of each of the papers opposite to the associated printing drum is actuated through the energization of an electromagnetic plunger so as to strike against the printing drum with the paper interposed therebetween whereby characters formed on the outer periphery of the rotating printing drum are selectively printed on the associated paper by controlling the striking time.
In this electromagnetic plunger type printing device, in order that the hammers of the printing device which correspond to the character rows on the printing drum adapted to be rotatably driven can precisely strike against the character rows, the common shaft of the hammers is journalled in the printer main body in a parallel relationship to the shaft of the printing drum. On the other hand, electromagnetic plungers for actuating the hammers are adapted to be mounted in a yoke and integrally secured to the printer main body to operatively connect between the hammers and plungers.
Thus, the hammers are mounted on their shaft in a precise position relative to the printing drum, but the yoke adapted to be mounted on the printer main body for maintaining the hammers and plungers in operative connection should be adjustably positioned so as to determine the striking force of the hammers which depends upon the operative connection between the hammers and plungers and thus, the adjustment of the mounting position of the yoke is troublesome.
In the printer in which the receipt paper and journal paper are arranged in parallel to each other, as the cutter device for cutting or perforating the receipt paper, use has been made of the cutter which includes a cutter and a cutter guide and is designed to cut or perforate the receipt paper interposed between the cutter and cutter guide by advancing the cutter into the slit in the cutter guide.
This type of prior art cutter device is designed to cause the cutting edge of the cutter to directly advance into the slit in the cutter guide and accordingly, the adjustment and maintenance of the relative position between the cutter and slit are difficult and present a problem in assembling the cutter device. And although it is desirable that the width of the slit in the cutter guide is limited to a value close to the thickness of the cutter to improve the sharpness of the cutter, it has been impossible to reduce the difference in sizes between the slit width and cutter thickness because of the above-mentioned reason and processing preciseness.
In the above-mentioned printer, an optical detector has been employed as means for detecting the position of the rotating printing drum to thereby select a character to be printed. Generally, since the printing drum is disposed within the printer, a disc having a plurality of openings therein is employed in combination with the printing drum for detecting the position of the rotating drum. In this case, a luminous element and a light receiving element are disposed adjacent to the opposite sides of the disc and accordingly, since the optical detector should be mounted in a limited space within the printer, the mounting of the detector is not easy because precise positioning of the detector is required and a separate cover should be attached to the detector for shielding the optical elements from external light.